And, in what was effectively their last attack, skipper Sinfield fed full-back Smith, who evaded two tired tackles to sneak over for a dramatic winning try.

Richards' accuracy looked to have steered the Super League leaders through against the reigning three-time champions.

Seemingly crucially, Sinfield had landed just four from eight attempts, three of which rebounded off the uprights, demonstrating the close nature of a game spoiled for the most part by the rain which wiped out the entire day's play next door in cricket's Roses Match.

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Conditions made for tough match - McClennan

But, with just a minute left of an error-strewn, yet pulsating quarter-final, the Wigan fans could scarcely believe their eyes when stand-in full-back Smith, deputising for the suspended Brent Webb, struck for his fourth try since returning from rugby union at Easter.

The last-gasp score condemned Wigan to only a third defeat under coach Michael Maguire as Leeds repeated their quarter-final win at Headingley against the same opposition in 2008.

Handling errors right from the start set the tone for the most tightly-contested but at times ugly of games.

Wigan front row forward Andy Coley was put on report for a dangerous tackle on centre Brett Delaney, while fit-again England skipper Jamie Peacock, back earlier than expected from a knee injury, was lectured by referee Phil Bentham for a high tackle on Sam Tomkins within two minutes of entering the action as a substitute.

Lee Smith also scored the winning try for Leeds in last year's Grand Final

The Rhinos enjoyed the early pressure but tries were always going to be scarce and even the normally reliable Sinfield hit the woodwork with his two early penalty attempts.

Richards, Super League's runaway top points scorer, then succeeded where Sinfield failed with three successful strikes to put his side into a 6-0 lead after 34 minutes.

But Sinfield eventually found his accuracy to claw the score back to 6-4 at the break, levelling eight minutes into the second half after Wigan substitute Liam Farrell was sin-binned for a late tackle on Danny McGuire.

Farrell had only just taken to the field as a replacement for Joel Tomkins, who had been led off with blood streaming from a facial wound after catching the stray boot of Leeds centre Keith Senior.

Leeds' best chance of a try came when Wigan winger Karl Pryce got back to defend Sinfield's grubber kick to the line seconds ahead of the advancing Jamie Jones-Buchanan.

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Wigan coach switches focus to Super League

But the visitors immediately cleared the danger, reclaiming the lead on 57 minutes with a fourth penalty from Richards after lively stand-off Tomkins' kick had caused confusion.

Sinfield and Richards then traded long-range penalties to leave the Warriors clinging to a two-point lead.

And Leeds, the 1999 winners, looked to have blown their last chance when centre Delaney's pass for fellow Aussie Scott Donald sailed straight ion front of the bemused winger and into touch.

But a scrum on the Wigan 20-metre line gave the Rhinos one last opportunity and Smith took Sinfield's pass before evading the tackles of Gleeson and Richards to win a memorable quarter-final.

Leeds coach Brian McClennan told BBC Sport:

"What a tough game, but what a time for the try to come.

"We hung in there, penalty for penalty. You don't see that too often today in rugby league.

"It was very difficult handling conditions. There was a lot of loose ball as a result of the weather, but both teams played with such intensity.

"Being at home counted a lot in the end as our supporters got behind us. And these Leeds boys are tough. When thy set their minds to it, they can get anything done.

"If it was close in the last quarter, we felt fairly confident because of our big-match experience," said McClennan.

"We're not being big-headed but, if it's close with 10 or 15 minutes to go, most teams get a bit edgy against us.

"It's still one step at a time for us. We'll see who we draw in the next one but it's been a hell of a ride so far."

Wigan winger Pat Richards told BBC Sport:

"We only played for 79 minutes, not 80 minutes and we're devastated.

"We knew it was going to be one of those days when points are hard to come by.

"But they're a great side Leeds. We're just disappointed to let ourselves down.

"We wanted to go all the way in this competition. Now it's not to be and it's hard to take."

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